TY - THES

T1 - Numerical analysis of a high speed large engine connecting rod

AU - Gschwandl, Timna Jakomijna

N1 - embargoed until 02-03-2025

PY - 2020

Y1 - 2020

N2 - This thesis presents the development and evaluation of a high speed large engine connecting rod (short: con-rod) for engines with a targeted peak firing pressure of 330 bar by the use of various numerical analysis approaches. For a primal assessment of the design of the developed con-rod, the most relevant parameters, such as the mass, the material or the con-rod ratio have been investigated. Consecutively, the design parameters have been compared with similar con-rods by generating a benchmark document. Following, an elasto-hydrodynamic simulation (EHD) in AVL EXCITE Powerunit has been conducted to assess the bearing of the con-rod. Thereby, the ability of the bearing to withstand the load from 330 bar peak firing pressure at various engine speeds has been investigated and further improved. With the input of the bearing loads from the EHD analysis, the finite element stress analysis under operational loads of the con-rod has been executed in Abaqus. Based on the stress situation of the con-rod, a high cycle fatigue investigation has been conducted in FEMFAT. Using this approach, the local fatigue safety of the con-rod has been evaluated. As a result, one area has been localized as critical with respect to fatigue safety. However, by suitable design adaptations the fatigue resistance can be assured. Finally, the influence of the tightening procedure on the bearing back contact pressure has been investigated in detail. Thereby, several tightening sequences and also the difference between a one step and a two step tightening has been compared with a parametric study. Moreover, the distribution of the contact pressure over the bearing width and the bearing angle has been analysed regarding its homogeneity with MATLAB. The study showed, that the tightening sequence and also the number of tightening steps has a significant influence on the homogeneity of the pressure distribution of the bearing. Summarizing, the conducted virtual workflow for the assessment of a conrod has shown informative results for the development of high speed large engines. Also the importance of the tightening procedure has become obvious. Thus, the engine design process and also the assembly procedure will be continuously improved by the involved company partner - AVL List GmbH.

AB - This thesis presents the development and evaluation of a high speed large engine connecting rod (short: con-rod) for engines with a targeted peak firing pressure of 330 bar by the use of various numerical analysis approaches. For a primal assessment of the design of the developed con-rod, the most relevant parameters, such as the mass, the material or the con-rod ratio have been investigated. Consecutively, the design parameters have been compared with similar con-rods by generating a benchmark document. Following, an elasto-hydrodynamic simulation (EHD) in AVL EXCITE Powerunit has been conducted to assess the bearing of the con-rod. Thereby, the ability of the bearing to withstand the load from 330 bar peak firing pressure at various engine speeds has been investigated and further improved. With the input of the bearing loads from the EHD analysis, the finite element stress analysis under operational loads of the con-rod has been executed in Abaqus. Based on the stress situation of the con-rod, a high cycle fatigue investigation has been conducted in FEMFAT. Using this approach, the local fatigue safety of the con-rod has been evaluated. As a result, one area has been localized as critical with respect to fatigue safety. However, by suitable design adaptations the fatigue resistance can be assured. Finally, the influence of the tightening procedure on the bearing back contact pressure has been investigated in detail. Thereby, several tightening sequences and also the difference between a one step and a two step tightening has been compared with a parametric study. Moreover, the distribution of the contact pressure over the bearing width and the bearing angle has been analysed regarding its homogeneity with MATLAB. The study showed, that the tightening sequence and also the number of tightening steps has a significant influence on the homogeneity of the pressure distribution of the bearing. Summarizing, the conducted virtual workflow for the assessment of a conrod has shown informative results for the development of high speed large engines. Also the importance of the tightening procedure has become obvious. Thus, the engine design process and also the assembly procedure will be continuously improved by the involved company partner - AVL List GmbH.

KW - high speed large engine

KW - connecting rod

KW - numerical analysis

KW - elastohydrodynamic analysis

KW - HCF analysis

KW - tightening procedure

KW - Schnelllaufender Großmotor

KW - Pleuel

KW - Numerische Analyse

KW - Elasto-hydrodynamische Analyse

KW - HCF Analyse

KW - Anziehprozedur

M3 - Master's Thesis

ER -